Inclusion Criteria:

1. Patients 18 years of age or over.
2. Histologically documented diagnosis of malignant GIST.
3. Immunohistochemical documentation of c-kit (CD117) expression either by the primary tumor or metastases using the DAKO assay.
4. Performance status 0,1, 2, 3 (ECOG)
5. Adequate end organ function, defined as the following: total bilirubin < 1.5 x ULN, SGOT and SGPT < 2.5 x UNL (or < 5 x ULN if hepatic metastases are present), creatinine < 1.5 x ULN, ANC > 1.0 x 109/L, platelets > 100 x 109/L.
6. Female patients of child-bearing potential must have negative pregnancy test within 7 days before initiation of study drug dosing. Post menopausal women must be amenorrheic for at least 12 months to be considered of non-childbearing potential. Female patients of reproductive potential must agree to employ an effective barrier method of birth control throughout the study and for up to 2 weeks (according to updated Invest. Brochure) following discontinuation of study drug.
7. Written, voluntary, informed consent.

Exclusion Criteria:

1. Patient has another malignant tumor in CR<3 years (except if the other primary malignancy is inactive and not requiring active intervention). Previous basal cell skin cancer or a cervical carcinoma in situ are allowed.
2. Patient with Grade III/IV cardiac problems as defined by the New York Heart Association Criteria. (i.e., congestive heart failure, myocardial infarction within 6 months of study)
3. Female patients who are pregnant or breast-feeding.
4. Patient has a known diagnosis of human immunodeficiency virus (HIV) infection.
5. Patients received chemotherapy within 2 weeks prior to study entry, unless the disease is rapidly progressing
6. Patients had a major surgery within 2 weeks prior to entry study
7. Patient with any significant history of non-compliance to medical regimens or with inability to grant reliable informed consent.
8. Previous treatment with Glivec®